XF 1.5Avatar customisation - auto-resize

Member

Hi, i am Aljaz.
I own a Minecraft server network and 1 extra server where i have personal email and XenForo forum.

I need some help with avatar resizing.
As i understood from other posts, XenForo uses 96x96 avatar images, but if user uploads a smaller image it wont be resized (at least in my case, idk for other forums)
i was searching for codes on google and other forums, but i did not find anything that i could help with.
I am not good with this because i have this server & forum only 4 days, so i am a total starter.

< example for current state

if possible it would be like this
so if the user uploads "wrong-size" image it would be fixed to correct size.
should work like "background-size: 100% 100%;" for background

Is it possible to setup a code on Appearance> Styles > second style > Style Property Groups > ????
And on what section? (avatar list item, visitor panel avatar)

I hope you can answer/help me and (i suppose) lots of other members/XenForo users